PB2114: BELANTAMAB MAFODOTIN FOR RELAPSED/REFRACTORY MULTIPLE MYELOMA: A REAL-WORLD OBSERVATIONAL STUDY UPDATE
Authors: Malin Hultcrantz, David Kleinman, Ravi Vij, Fernando Escalante, Michel Delforge, Nirali Kotowsky, Jacopo Bitetti, Natalie Boytsov, Leena Camadoo-O’byrne, Lindsey Powers Happ, Mujib Rohman, Guillaume Germain, Mei Sheng Duh, François Laliberté, Malena Mahendran, Ana Urosevic, Hans C. Lee
Journal: HemaSphere (2023)

Topic: 14. Myeloma and other monoclonal gammopathies - Clinical Background: A prior retrospective analysis of US patients with relapsed/refractory multiple myeloma (RRMM) suggested that patients treated with belantamab mafodotin (belamaf), a B-cell maturation antigen-targeting antibody-drug conjugate, experienced similar outcomes to those who received belamaf in the pivotal DREAMM-2 study. Aims: This updated analysis aimed to characterize patients, assess occurrence and management of ocular adverse events (AEs), and evaluate belamaf effectiveness in a real-world setting. Methods: This retrospective, longitudinal, observational study used data sourced from the US electronic health record-derived Flatiron Health de-identified database (01/01/2011–06/30/2022). Eligible patients had a confirmed MM diagnosis, initiated belamaf after FDA approval (08/05/2020; first administration=index date), were ≥18 years old at index, and had chart abstraction data for ocular safety and treatment effectiveness. Data on ocular AEs were reported separately for all patients and patients with ≥4 months of follow-up to allow for sufficient follow-up to evaluate incidence of ocular AEs and their mitigations. Tumor response was assessed in all patients, along with Kaplan-Meier estimates of duration of response (DoR), overall survival (OS), and progression-free survival (PFS). Results: Of the 184 patients included in the study, mean age was 68.7 years; 64% were White and 47% were female. Eastern Cooperative Oncology Group (ECOG) status was ≥2 in 28% patients, 62% had received ≥5 prior lines of therapy, and 82% were triple-class refractory. Median (IQR) follow-up was 4.1 (1.9–8.5) months. Among patients with ≥4 months of follow-up (n=94), 75% had ≥1 ocular AE, with keratopathy and blurred vision being the most frequent. Mean (SD) time to first ocular AE was 39 (34) days. Most ocular AEs were managed by therapy hold (69%; of which 73% restarted belamaf) and/or AE treatment (63%). The median dose hold due to ocular AEs was 43 days (physician-reported keratopathy: mild, 21 days; moderate/severe, 56 days). In all patients, 39 (21%) had a derived tumor response based on serum free light chain levels, (partial response: 74%, very good partial response: 51%). For all patients, the estimated median DoR was 9.1 months, PFS 4.5 months, and OS 7.9 months, while the 6-month DoR rate was 57%, PFS rate was 46%, and OS rate was 58%. Summary/Conclusion: Overall, belamaf was effective in the real world setting in heavily pre-treated patients with RRMM and with limited therapy options. The AE profile was consistent with DREAMM-2. Ocular AEs were manageable and despite their occurrence, a high percentage of patients remained on treatment, suggesting belamaf may fill an unmet need for triple-class refractory patients with RRMM. Funding: GSK (218905) This abstract was previously submitted to the American Society of Clinical Oncology (ASCO) Annual Meeting, June 2–6, 2023, and is submitted on behalf of the original authors with their permission. ©2023 American Society of Clinical Oncology, Inc. Reused with permission. All rights reserved. Figure. Ocular AE and belamaf responseKeywords: Multiple myeloma, Real world data